With prior art arrangements, flat spins were commonly broken by a single towline parachute deployed from the rear of the aircraft. The parachute exerted an anti-spin torque by exerting a force, opposite to the spin, through the moment arm extending from the aircraft center of mass to the point of chute attachment at the midline of the rear fuselage. These spin-recovery parachutes were frequently installed for use during flight testing of the aircraft, but their installation not only introduced error into the results of those flight tests but created so many design problems that the chutes were seldom incorporated into operational fighter or commercial planes. The large diameter parachutes and long towlines required stowage compartments in the rear fuselage, and the compartments produced undesirable deviations from the production contours of the air craft. The large chute forces in addition, required substantial structural reinforcement of the aircraft to enable it to withstand the high design load of the chute, and such reinforcements altered the mass distribution of the aircraft and its subsequent flight test performance.
Wingtip recovery parachutes, developed and tested during World War II, avoided some of the above difficulties but created problems of their own. By enabling or facilitating "rolling into the spin," the wingtip parachute can apply a rolling moment to the aircraft to produce a significant gyroscopic recovery moment. ("Rolling into the spin" is a gyroscopic phenomenon, well known to fighter pilots, which causes the rate of aerodynamic spin to decrease.) Each wingtip of the aircraft is equipped with a stowed parachute and, in the event of spin, one of them is deployed; the pilot must determine the direction of the spin and choose the appropriate wingtip chute. Unfortunately, the pilot is likely to be severely disoriented during a spin and unable to determine quickly which wingtip chute to deploy; if the pilot chooses the wrong one, the aircraft will "roll out of the spin," not into it, and the spin rate will increase. Furthermore, because the wingtip chutes cause rather violent recoveries, usually followed by spins in the opposite direction, the wingtip chute must be released immediately upon spin recovery. The continuing disorientation of the pilot, sometimes resulting from "eyeballs out" g's, renders this tricky parachute jettison even more difficult.